How to Become the IT Manager of Your Installation – Part Two

Joe Loucks

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On September 10th In IP Solutions, IP Tech Tips, Video Surveillance
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Once the range of IP addresses that are currently being used by a client’s LAN has been discovered by using the ipconfig /all command, installation technicians can start to plan the specific static IP address that will be input into the programming of a physical security device such as an IP camera, controller, or intercom.

As we saw in the previous blog post, the local network we’re going to use has IP addresses that start with 192.168.1 in the first three of the four positions. This type of address with four positions, each having valid numbers between 0 and 255, is called the “IPV4” addressing method. We also determined that this client’s network has an active Dynamic Host Control Protocol (DHCP) server which is providing temporary IP addresses along with the common subnet mask and default gateway addressing information to devices such as PCs, smartphones and tablets that send in requests for addressing sets.

Now we need to determine what addresses constitute the “DHCP field,” these being the group of addresses that the DHCP server is programmed to provide. To get this information we will need to access the local router where the DHCP server is located and check it out.

Accessing the router is a very simple process. From the “ipconfig” command we can gather the “default gateway” IP address, which is the local area network address of the router, in this example 192.168.1.1.  Opening Internet Explorer from any network connected PC and entering the router’s address into the Explorer addressing line will bring up the username and password challenge from the router. You must obtain this password information from the client; without router access you risk the real danger of duplication of an IP address which will cause major problems with the devices whose addresses have been duplicated.

Once in the router we will look for the DHCP field to get the information we need.

Here we see that the DHCP server is turned on, and will issue fifteen addresses from 192.168.1.100 to 192.168.1.114. So we can select any static local IP address from 192.168.1.2 to 192.168.1.99, or select an address from the range of 192.168.1.115 to 192.168.1.254. Whether the address you select to use has a lower or higher number value in the last section doesn’t matter; the device will perform the same either way.

Often there are both static and dynamic IP addresses on the same local network. So once we’ve selected an address, for example 192.168.1.50, then we should test that address on the LAN to make sure that there isn’t another device that has that same address.

To test the address we’ve selected we’ll use the “ping” command.

This test indicates by the “request timed out” responses that at the time this test was performed there was no active device on the local network with the address 192.168.1.50. Now we can be sure that the address we’ve selected is usable on this network.